1. Technical Field
The present invention relates generally to techniques for content delivery.
2. Description of the Related Art
It is known in the art for a content provider to outsource its content delivery requirements to a content delivery network (a “CDN”). A content delivery network is a collection of content servers and associated control mechanisms that offload work from Web site origin servers by delivering content on their behalf to end users. A well-managed CDN achieves this goal by serving some or all of the contents of a site's Web pages, thereby reducing the customer's infrastructure costs while enhancing an end user's browsing experience from the site. For optimal performance, the CDN service provider may maintain an objective, detailed, real-time view of the Internet's topology, reliability, and latency, and this view may then be used to power a dynamic DNS-based system to direct end users to the best CDN server to handle a particular request.
Digital Rights Management (DRM) refers to the technology used for the protection of digital media content, typically audio or audiovisual works. DRM works by encrypting the content before distribution, and by limiting access to only those end-users who have acquired a proper license to play the content. The DRM license enforcement is done at the player/client, and therefore, the integrity of the client-side (of DRM) is critical for the scheme to work. Microsoft, Real and Apple have developed proprietary DRM technologies for their audio and audiovisual content distribution. Apple's DRM technology is used in its iTunes music service. Microsoft and Real Networks support DRM protection for both on-demand and live media content. There are some standardization efforts around DRM (MPEG4/ISMA and Open Mobile Alliance), but these standards are still in the specification stage.
An end-to-end DRM system typically comprises three (3) parts: encryption, business-logic and license-delivery. DRM starts with the encryption of the content. Once the content is encrypted, a key is required to unlock the content. The encrypted content can be delivered through any number of delivery methods: HTTP, streaming, FTP, P2P, email, or the like. An end-user who desires to play the content visits an e-commerce web site and transacts with the business-logic process, usually involving one of registration, login, and/or payment; once this is done, the end-user is issued a license to play the content. The issued license typically comprises (i) a key (for decrypting the content), (ii) a set of rights (e.g. play exactly once, play for 30 days, or the like), and (iii) with the property that the license is valid only on the end-user machine to which it is issued. When an end-user attempts to play the DRM protected content, the player first checks the license cache on the machine, and if a license is found, the playback starts by decrypting the content. If a license is not found, the player attempts to get a license, typically from the storefront URL that is embedded in the content. Ultimately, it is the player/client that enforces the DRM. In a typical DRM scenario, a media file (e.g., a stream) is encrypted by a packager component using a key. Alternatively, the stream can be encrypted on the fly by an encoder. A streaming Server serves the encrypted stream to an end user browser's media player. As noted above, the player needs to get a license (which includes the key) from a license server to decrypt and play the content.
In the past, administration and management of the DRM license keys has taken place in a centralized manner, primarily to address security issues. It would highly desirable to be able to leverage the distributed nature of a content delivery network to facilitate a distributed (non-centralized) license delivery infrastructure. This present invention addresses this need.